Many Type is not defined.

Describe the bug When types are generated the Maybe type is not included.

To Reproduce Steps to reproduce the behavior:

1. Use the following config:

overwrite: true
schema: './src/schema.ts'
generates:
  src/types/generated.ts:
    - add: '// THIS IS A GENERATED FILE, DO NOT EDIT IT!'
    - 'typescript-server'
    - 'typescript-resolvers'
require:
  - ts-node/register

1. Include typedefs & resolver and create executableSchema.
2. Run codegen.

Expected behavior All types are correctly genereted except for the Maybe type, that one is missing.

Schema/Documents Ofcourse create an executableSchema from the following.

export const typeDefs: DocumentNode = gql`
  type Field {
    id: ID!
    testId: ID!
  }

  type Query {
    FieldsByTest: [Field!]
  }
`;

export const resolver = {
  Query: {
    FieldsByTest: (_) => {
      return [];
    },
  },
};

Environment:

• OS: Mac OS 10.12.6
• Codegen: ^0.15.2
• Node: 10.14.1

[thomasfedb]

In the config file above 'typescript-server'.

[thomasfedb]

I’m sure a PR would be appreciated @Pruxis. Shouldn’t be difficult.